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-rw-r--r--src/com/android/camera/ui/focus/LensRangeCalculator.java71
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diff --git a/src/com/android/camera/ui/focus/LensRangeCalculator.java b/src/com/android/camera/ui/focus/LensRangeCalculator.java
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+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.camera.ui.focus;
+
+import android.annotation.TargetApi;
+import android.hardware.camera2.CameraCharacteristics;
+import android.os.Build.VERSION_CODES;
+
+import com.android.camera.ui.motion.LinearScale;
+
+/**
+ * Compute diopter range scale to convert lens focus distances into
+ * a ratio value.
+ */
+@TargetApi(VERSION_CODES.LOLLIPOP)
+public class LensRangeCalculator {
+
+ /**
+ * A NoOp linear scale for computing diopter values will always return 0
+ */
+ public static LinearScale getNoOp() {
+ return new LinearScale(0, 0, 0, 0);
+ }
+
+ /**
+ * Compute the focus range from the camera characteristics and build
+ * a linear scale model that maps a focus distance to a ratio between
+ * the min and max range.
+ */
+ public static LinearScale getDiopterToRatioCalculator(CameraCharacteristics characteristics) {
+ // From the android documentation:
+ //
+ // 0.0f represents farthest focus, and LENS_INFO_MINIMUM_FOCUS_DISTANCE
+ // represents the nearest focus the device can achieve.
+ //
+ // Example:
+ //
+ // Infinity Hyperfocal Minimum Camera
+ // <----------|-----------------------------| |
+ // [0.0] [0.31] [14.29]
+ Float nearest = characteristics.get(CameraCharacteristics.LENS_INFO_MINIMUM_FOCUS_DISTANCE);
+ Float hyperfocal = characteristics.get(CameraCharacteristics.LENS_INFO_HYPERFOCAL_DISTANCE);
+
+ if (nearest == null && hyperfocal == null) {
+ return getNoOp();
+ }
+
+ nearest = (nearest == null) ? 0.0f : nearest;
+ hyperfocal = (hyperfocal == null) ? 0.0f : hyperfocal;
+
+ if (nearest > hyperfocal) {
+ return new LinearScale(hyperfocal, nearest, 0, 1);
+ }
+
+ return new LinearScale(nearest, hyperfocal, 0, 1);
+ }
+}